7x2=20.42

Solution for 7x2=20.42 equation:

7x^2=20.42

We move all terms to the left:

7x^2-(20.42)=0

We add all the numbers together, and all the variables

7x^2-20.42=0

a = 7; b = 0; c = -20.42;
Δ = b2-4ac
Δ = 02-4·7·(-20.42)
Δ = 571.76
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{571.76}}{2*7}=\frac{0-\sqrt{571.76}}{14}
=-\frac{\sqrt{}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{571.76}}{2*7}=\frac{0+\sqrt{571.76}}{14}
=\frac{\sqrt{}}{14}
$